I know mechanical pencils are prohibited, but what about mechanical erasers? I prefer them over block erasers because they're more precise.

Are you talking about one where you click it to make more eraser come out of the end? Other than that I'm not sure what you could mean by 'mechanical eraser'. The language of the LSAC rules just says that erasers are allowed but does not define what types. I would guess that since they banned mechanical pencils (for whatever reason, why is still a mystery to me!), and that since a 'mechanical' stick eraser is similar to and resembles a mechanical pencil, that it would qualify as a banned item.

Play it safe and get used to using a block eraser. Hello Kitty ones are kinda cool still!

Simply to avoid any potential trouble at the test center (you don't want that, you'll already be under enough pressure/stressful circumstances) I say play it safe and go with a standard eraser to avoid having an extra distracting thing to stress and worry about. While worrying/stressing about the test while waiting in line and checking in I sure as $hit wouldn't want to also have the extra worry of 'are they going to take my eraser away'.

You're right; probably best to play it safe. But you'd think LSAC would be more clear and unambiguous...

You'd think, but then again they are old people that are familiar with and used to using old fashioned tools like wooden pencils, slide rulers, an abacus for math, spears and torches to chase enemies away from the village and to suppress native uprisings , etc. If they walked into an Office depot or a computer store to check out new things they could risk going into some sort of culture shock and get really confused trying to figure out how to use the 'fancy new fangled' devil devices!